ECMWF quality information (status 2018-06-13; source: https://confluence.ecmwf.int/display/CKB/ERA-Interim+known+issues : ERA-Interim known issues: 1. Surface photosynthetically active radiation (surface PAR) values are too low 2. Convective Available Potential Energy (CAPE) values are erroneously zero 3. ERA-Interim issues with cloud cover 4. Sea Surface Temperature has values over land in ERA-Interim and other ERA products 5. Anomalies at certain dates and locations 6. Over oceans geopotential (and potentially derived fields too) shows a 'spectral ripples' pattern. 7. It is not possible to obtain full (archived) resolution ERA-Interim data from the point and click web interface. Instead you get: a. For spectral data, when grid=128 is selected, automatic truncation to T213 occurs. b. The option "Grid default (as archived)" gives a 0.75x0.75 lat/long grid for both spectral and grid point data, again with automatic truncation to T213 for spectral fields. c. The Gaussian grids all appear to be full grids, not reduced, with no means of requesting the latter. d. There is no T255 option 8. Sunshine duration is defined in a non-standard manner which leads to underestimation of this quantity.
European Centre for Medium-Range Weather Forecasts